You now have a wide image. The reason we have an image width of 1500 pixels is to try and cover all screens and resolutions. If we had set the image to a width of 640, the border would tile across larger screens with higher resolutions.

You have basically completed a border background – you have a border along with your background, but let's make this more exciting.

We're going to bevel this background. To do this we're going to use the selection and the buttonize functions.

Double-click on the Selection tool in your tool palette. Set the coordinates as follows:
Left = 0
Right = 100
Top = 0
Bottom = 100

Set your foreground style to Pattern (click on the arrow in your foreground style box and choose the second icon from the right) and your foreground texture to None (click on the arrow in your foreground texture box and choose the icon on the right). Then click into your foreground style box and choose your border image from the Pattern drop-down box (Scale = 100, Angle = 0).

Click into the image to fill it with your background.

As you can see, there is a black line between the sections. This is the problem with most backgrounds, you can see their tiling effect. We'll get rid of that.

Go back to your background image and undo the buttonize function (Ctrl+Z).

Now that we have bevelled the border, we'll have to make the canvas smaller again: Go to Image || Canvas Size and set:
New Width = 1500
New Height = 100
Center Image Horizontally/Vertically = both checked

As you can see, we're back to our bevelled border.

To test this background, go back to your 300 x 300 image and click on the Floodfill tool in your tool palette.

Click into your foreground style box and select your border image again in the Pattern drop-down box (you have to choose your image again so that it is applied with the changes made).

Now click into your image to fill it with the changed border background. See how that got rid of that seam in the background?

An added option now would be to turn the border around so that the lighter edge of the bevel is on the white side of the border.

To do this, double-click on the Selection tool and set the coordinates as follows to select the border only:
Left = 0
Right = 100
Top = 0
Bottom = 100

Then mirror the border: Go to Image || Mirror.

Deselect by right-clicking into the image. Now you have a nice bevelled background.